OBJECTIVES:9/21/09

1. Describe the differences between the English and Metric System.

2. Explain why using one system world-wide would be useful.

3. Convert between English and metric units.

Why do we measure things?

To compare things

To determine exact amounts

To collect data

What is the “English” System?

What we commonly refer to as the “English” system: United States Customary System

Many of the units have historical basis that goes back further than the Middle Ages!EX: 3 Barleycorns = 1 Inch (YES - the length of a corn of barley!!)Can you see potential problems?

Activity!

You and your partner: Come up with a novel or unique way

to measure the length of: The lab table Your chair leg Your height

Use the SAME unit of measurement for all of them!!!

Report your data to Ms. Smyder

DISCUSSIONWhat did you learn from this activity?

What are the problems you encountered when trying to compare measurements?

Mathematically, how easy or difficult would it be to convert between you and your classmates’ units?

The Metric System or SI

First adopted in France in 1791.The system of measurement used by most of the world.International System of Units (Système International d'Unités ) also known as the SI system.System used by ALL SCIENTISTS!!

Why is the Metric System So Great?

It is based on the number 10!!!!!

1 meter = 10 decimeters1 decimeter = 10 centimeters1 centimeter = 10 millimeters

IT’S SO EASY!

VOCABULARY!

Standard

An exact quantity that people agree to use for comparison.

SI

System of measurement used world-wide in science.

Metric System

The FIRST system of measurement that was based on units of ten.

Prefixes in the Metric System

Used with the base unit to indicate (show) the multiple of ten that is being used with the base unit.

Base units

The basic unit of a type of measurement

Length – MeterMass – GramVolume - Liter

Length

Distance between two points

Meter

Metric base unit of length

Meterstick

Tool used to measure length

Volume

Amount of space occupied by an object

Liter

Metric base unit used to measure volume.

Graduated Cylinder

Tool used to measure volume of a liquid.

Mass

Amount of matter that an object has.

Gram

Metric base unit used to measure mass.

Balance

Tool used to measure mass.

Density

Mass per unit volume.

Time

The interval between two events.

Second

SI base unit of time.

Temperature

A measurement of heat.

Thermometer

Tool used to measure temperature.

Celcius

Temperature scale used in most laboratories.

Kelvin

Official SI unit of temperature.

PREFIX TABLE

PREFIX Means Multiplied…

Kilo - 1000x

Hecto - 100x

Deka - 10x

BASE UNIT

Deci - 0.1x

Centi - 0.01x

Milli - 0.001x

Ladder Method

How do you use the “ladder” method?

1st – Determine your starting point.

2nd – Count the “jumps” to your ending point.

3rd – Move the decimal the same number of jumps in the same direction.

4 km = _________ m

Starting Point Ending Point

How many jumps does it take?

4.1

__.3

__.2

__. = 4000 m

Try these conversions using the ladder method.

1000 mg = ____1__ g 1 L = __1,000_ mL 160 cm = _1,600__ mm

14 km = _14,000_ m 109 g = _0,109__ kg 250 m = __0.25__ km

Conversion Practice

Compare using <, >, or =.

56 cm < 6 m 7 g > 698 mg

x10x100

x100

10

1000

100

Write the correct abbreviation for each metric unit.

1) Kilogram _kg__ 4) Milliliter __ml_ 7) Kilometer _km__

2) Meter _m__ 5) Millimeter __mm_ 8) Centimeter __cm_

3) Gram __g__ 6) Liter ___l__ 9) Milligram _mm__

Try these conversions, using the ladder method.

10) 2000 mg = ___2g__ g 15) 5 L = __5000_ mL 20) 16 cm = ___160_ mm

11) 104 km = __104,000_ m 16) 198 g = __0.198__ kg 21) 2500 m = __2.5__ km

12) 480 cm = __4.8_ m 17) 75 mL = __0.075_ L 22) 65 g = _65,000_ mg

13) 5.6 kg = _5600_ g 18) 50 cm = _0.5_ m 23) 6.3 cm = _63__ mm

14) 8 mm = _0.8__ cm 19) 5.6 m = _560__ cm 24) 120 mg = 0.120__ g

Metric Conversion Challenge